Today, however, may prove to be his toughest test. After a painstaking, three-year, $8 million investigation, the former head of Scotland Yard issued an 832-page report confirming what common sense and all previous inquiries had suggested: that Diana, Princess of Wales, was killed in a Paris car accident because her chauffeur was drunk and speeding as he tried to outrace paparazzi on motorbikes. The Queen didn't order it, nor the CIA, nor MI6 or MI5 or anyone else it was simply tragic bad luck.
Stevens's inquiry interviewed more than 300 witnesses, collected over 600 exhibits and used new computer technology to reconstruct the path of the 1994 Mercedes inside the Paris tunnel where it crashed. His investigators spoke to the head of MI5 (British domestic intelligence) and MI6 (foreign intelligence) as well as Prince Charles, who was reportedly even asked whether he had plotted to assassinate his ex-wife. The CIA and other U.S. agencies were asked for information. Stevens said the huge report and its public release were intended to show how systematically the investigators went about their business, so that there could be public confidence in his conclusion that "there was no conspiracy to murder any of the occupants of that car."
Indeed, Stevens doesn't hide the fact that he is trying to drown the conspiracy theories that have swirled around Diana's death in a sea of boring fact. "I know this report will be subject to greater scrutiny than anything I have done before," he said, "and people may continue to raise issues it is inevitable. But we believe that the public should have the opportunity to view the investigation in its entirety. This will allow for properly informed debate about the evidence rather than discussions based on theory and speculation."
So what theories did he knock down? In short, he concluded that no one had the combination of motive, means and opportunity to make any murder accusation credible.
• Motive? Mohammed al-Fayed, the father of Dodi, who was also killed in the crash, contends the British establishment bumped off Dodi and Diana to hide her pregnancy or to keep them from getting married. But Stevens concluded on the basis of hospital records, tests on blood in the destroyed car and talking to Diana's friends who knew her menstrual cycle that she was not pregnant at the time of her death. And as for engagement to Dodi, he had bought a ring, but had not yet proposed, "and we believe she never saw that ring," said Stevens. In all her conversations with her friends, Diana said she was coming home to England to see her children. "None of them has indicated to us that she was either about to or wished to get engaged. Her last conversations with friends and confidantes were to the contrary." So even if dark forces were bugging her phone, and the British establishment or the Queen or Prince Philip or the head of MI6 were horrified at the prospect of a non-white, Muslim half-brother to the future King of England, they would have had no impetus at that stage to put a murder plot in motion.
• Means? Stevens found no ties between Henri Paul, the driver of the car who lost control, and French or British intelligence. And he said there was no doubt that Paul's blood had at least twice the alcohol level permitted to British drivers. He was also driving at 61-63 miles per hour, twice the speed limit in the tunnel where the car crashed.
• Opportunity? The helter-skelter movements of Dodi Fayed and Diana in the hours before the crash, with last-minute changes of plan Paul had been off duty until shortly before he got in the car, which left from the back of the hotel instead of the front, as expected meant a murder operation of this complexity, to provoke a crash on an unanticipated route, could not have been mounted.
• Loose ends? The celebrated white Fiat Uno that scraped the Mercedes before it crashed has still not been found. Stevens attacked head-on the idea that James Andanson, a photojournalist who owned such a car and later was found to have committed suicide, was a secret agent and was involved in the Diana crash. Stevens found Andanson had been home with his wife that night, before flying the next day to an assignment in Corsica.
It sounds convincing, but will it put Diana conspiracy theories to rest? For most people, yes. But for conspiracy theorists and tabloid editors who see sales jump every time they can contrive a reason to put Diana's picture on the front page, probably not. Already this week, the blogs were buzzing with a report from a British newspaper claiming that "U.S. security services" had been bugging Diana's hotel room on the night of her death, prompting a highly unusual and direct refutation by the National Security Agency, the agency in charge of such things. "NSA did not target Princess Diana's communications," said a spokesman.
Still, in a complex event with lots of witnesses, there will always be an anomalous bit of evidence someone whose recollection differs from the mainstream, or physical evidence that can be inserted into the jigsaw in a new way. "Some people need conspiracy theories," says Cary Cooper, a professor of psychology and health at Lancaster University. The loved one of someone who dies may find it easier to bear if the death can be viewed as something other than a random tragic accident. That may explain Mohammed al Fayed's total conviction that his son was murdered. He called the report "shocking" and his lawyer said many questions remained. Stevens would say only that al-Fayed was "a genuinely grieving parent."
The huge emotional outpouring Diana's death provoked around the world means a similar sense of loss may be at work among those who never met her. "Some people have a predisposition to believe in conspiracies. They' re people who need structure, who want there to be an order in the world, who can't believe that unhappy events can just occur," says Cooper.
Peter Knight, a lecturer in American Studies at the University of Manchester who studies conspiracy theories, agrees that "if a major event happens, people want a major cause behind it." But he notices other trends at work in the persistence of Diana conspiracy theories. "Over the past 50 years, there's been a shift from scapegoating minorities 'the Jews did it, the blacks did it' to blaming people in power, like the royal family, the government, intelligence agencies. That's always been a bigger theme in the U.S. than in Britain, but Britain, indeed Europe as a whole is following the U.S. in this respect."
Being convinced that a conspiracy of elites killed Diana, the People's Princess, just fits into the zeitgeist. Says Cooper: "Your successor, and your successor's successor, is going to be writing about Diana conspiracy theories."